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    //字符串操作方法
    // 1.concat('字符串1','字符串2'...)
    var str = 'andy';
    console.log(str.concat('blue'));

    // 2.substr ('截取的起始位置'，'截取几个字符')
    var str1 = '改革春风吹满地';
    console.log(str1.substr(2, 2));

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